Rayo currently lead Jose Mourinho's men in the table by three points, and the fomer Spain international believes that his side can cause further misery for the reigning Spanish champions.
Last season's fixture between the two sides ended 1-0 to Los Blancos in a nervy game at Campo de Futbol de Vallecas, but Jemez maintains that he will not deploy any special tactics or approach.
"This is the game that players require the least motivation from me for. When you're playing against big teams, you have an excess of motivation," the 42-year-old told Marca.
"If I push them any further, I'll drive them up the wall. In fact, I even need to calm them down a bit! We want to be that team which causes an upset, and wins the three points against a team that's been feeling a bit of discomfort, but will wake up sooner or later.
"If I want us to be brave against any team, it's this one. The other day against Atletico, we didn't get stuck in during the first half, and in the second, with a different approach, we almost managed to get back into it.
"I hope we don't repeat that mistake, and play with pride this time, pushing high up the pitch and keeping the ball, so we can see if we have the talent to make the most of our opportunities," he said.
Rayo host Real Madrid later on Sunday. Kick-off is at 21:30CET.